One of the United States’ greatest successes in the Iraq war was in Anbar, where U.S. military forces and a remarkable tribal uprising inflicted a stunning defeat upon al-Qaeda in Iraq (AQI), the forerunner of today’s Islamic State (or ISIS). From shortly after the U.S. invasion of Iraq in 2003 until 2006, Anbar, the country’s westernmost province and a Sunni stronghold, was the center of an entrenched insurgency, which by early 2006 was threatening Baghdad. Then in the fall of 2006, just as U.S. leaders were considering the prospect of defeat, Sunni tribes in Ramadi, the capital of Anbar, formed a movement to partner with the Americans against AQI. This movement came to be known as the Anbar Awakening. Over the course of seven months of heavy fighting, the tribes, together with U.S. forces, overcame AQI in Ramadi, the provincial capital of Anbar. The awakening spread to the rest of the province and then to elsewhere in Iraq. AQI was pushed back, violence dropped, and the country witnessed a period of uneasy stability.

In the years that followed, the Anbar Awakening came to be seen as a turning point in the Iraq war and a model for how to defeat insurgents and terrorists. The U.S. officers of the time, including General David Petraeus and Colonel Sean MacFarland, enjoyed well-earned acclaim, while military strategists, analysts, and policymakers hailed the policies used in Anbar—such as increasing troop presence and empowering local tribes—as a leading example of how to conduct a counterinsurgency. There were widespread calls from politicians, generals, and analysts in subsequent years for the United States to attempt a similar “awakening” with the Pashtun tribes of Afghanistan, and the idea of working with tribes has influenced U.S. policy debates over how to handle the Syrian civil war. Anbar had become the foremost lesson in how counterinsurgency, and U.S. intervention writ large, could succeed.

Yet from today’s perspective, the victories of Anbar look fleeting. In